1. Field of the Invention
The present disclosure generally relates to airfoils.
2. Description of the Related Art
Multiple airfoils are typically used within turbine engines. For example, engine stators include a plurality of stationary or variable vanes having an airfoil shape.
During use in engines, such airfoils can experience airfoil bulge, a condition in which the opposed walls of the airfoil expand outward into the engine gas path due to the high temperatures in which the airfoils are used and/or the pressure difference between the interior and the exterior of the airfoils. Such bulge deforms the airfoils so as to temporarily or permanently alter their aerodynamic properties, which can significantly reduce the aerodynamic efficiency of the engine. In extreme cases, airfoil bulge can lead to airfoil rupture, which can cause substantial damage to the engine.
Prior solutions to airfoil bulge have included the provision of auxiliary longitudinal ribs within the airfoil that extend along the length of the airfoil and connect the opposed walls of the airfoil. Although such additional ribs are effective in reducing airfoil bulge, such a solution increases the number of internal surfaces of the airfoil and therefore the difficulty in cooling the airfoil. In addition, the additional use of ribs can increase the difficulty in providing baffles within the airfoils that control the flow of cooling air through the airfoils. Furthermore, the addition of ribs can significantly increase, the weight of the airfoils, and therefore the engine in which they are used.